A person may encounter radioactive radiation (also referred to as nuclear radiation), for example artificial nuclear radiation emitted by nuclear power reactors or by systems, for example accelerators, or materials used for medical applications. Furthermore, natural radioactive radiation may occur in certain materials. The materials may undergo concentration processes that may lead to an elevation of their radiation levels. Nevertheless, such materials may be used in everyday products, for example in industry or construction, where they may be used without protective measures such as walls configured to shield from the radiation.
Furthermore, also someone who has no known contact with the described sources of radioactive radiation may nevertheless feel safer if he or she had a sensor for the radioactive radiation at his or her disposal.
As an application of nuclear radiation or systems emitting nuclear radiation and/or an awareness of the radiation increases, a requirement for portable sensors detecting such radioactive radiation may also increase. In order to enable a large number of the above described group of potential users to afford and use such a radiation sensor, a simple construction, small size, simple use and/or a low price may be desired. Such a radiation sensor may for example be configured to detect gamma radiation. Gamma radiation may also be referred to as gamma rays, gamma photons or gamma quanta. In the context of this application, the term “gamma radiation” (and its synonyms) may refer to electromagnetic radiation with a quantum energy above approximately 40 keV.
Usually, gamma radiation may be detected by means of a gaseous ionization detector, like for example a Geiger-Muiller tube. Such gaseous ionization detectors may require a relatively large volume for a detection of gamma radiation, such that a miniaturization may be difficult.
Alternatively, traditional gamma ray detectors may use semiconductor materials for a direct detection of gamma photons. However, an interaction probability, i.e. the probability that a gamma photon will interact with the semiconductor material, for example by means of a photoelectric effect, Compton scattering or pair production, may be very low, at least compared to an interaction probability for charged particles, and also compared to electromagnetic radiation with a lower energy, for example electromagnetic radiation in a visible wavelength range. Silicon detectors may therefore primarily be used for a detection of a beta decay, which may lead to a release of an electron. Such a beta decay electron, being a charged particle, may have a detection probability of almost 100% in a silicon detector. The detection probability for a gamma photon, however, would be much lower in the silicon detector. In order to increase the detection probability for the gamma photons, a semiconductor with a higher atomic number may be used as the detector material. For example germanium (with an atomic number of 32, as opposed to 14 for the silicon) may be used. However, for an acceptable detection probability, a large volume of the germanium (or, more generally, the semiconductor) may still be required, which again makes a miniaturization difficult. Furthermore, germanium is very expensive.